Prepare the pork belly: Place pork belly on a rimmed baking sheet. Stir together salt, sugar, chile powder, ground coriander, and orange zest in a small bowl. Rub salt mixture all over pork; discard any remaining salt mixture. Wrap pork belly with plastic wrap, and chill at least 6 hours but no longer than
Preheat oven to 450°F. Unwrap pork, and place, fat side up, on a lightly greased wire rack. Place rack on baking sheet, and bake in preheated oven until golden brown and crispy, 45 minutes.
Reduce oven temperature to 250°F, and cook pork until tender when pierced with a fork, 45 minutes to 1 hour. Cool to room temperature, about 20 minutes. Cover with plastic wrap, and chill until firm, 45 minutes to 1 hour.
Prepare the spicy mustard sauce: Whisk together mustard, sour cream, olive oil, vinegar, and cayenne pepper in a small bowl until well combined. Set aside.
Cut pork into 1/2-inch-thick slices. Heat pork in a large skillet over medium until warmed through, 3 to 5 minutes per side.
Divide Swiss cheese evenly among tortillas. Top evenly with deli ham and hot pork belly slices (about 3 ounces pork belly per taco). Drizzle each with 1 1/2 tablespoons of the mustard sauce, and top each with 1/2 tablespoon of the pickles. Serve immediately.